You probably won't want to hear this answer!
But I think you need to learn to edit and sell your own work.
There are hundreds of great writing and editing books out there and you need to devour them. Then you need to read read read in your own genre to find out what works and what sells. Then you need to practise practise practise until you've honed that skill. Writing is a craft like any other, like learning to play the piano.
As the other posters have suggested, if you really aren't prepared to do that, you MAY find a co-author (the @NeilFein link has some suggestions) but I can't see it being easy. For these reasons:
Most good writers aren't going to want to write someone else's story unless they're ghostwriting for a reasonable sum. Are you planning on paying someone upfront to write and sell for you? Or are you expecting them to put in all the work upfront with potentially no return down the line?
There are editing services out there (some amateur and some professional) and I have a team of beta readers who are experienced authors themselves and they edit my early drafts in return for me editing theirs. I have used professional editing services like The Literary Consultancy, a UK-based edit and sell service, where they pitch your book to agents if they think it's good enough. And my existing agents have hired ex-in-house professional editors from publishing houses to assist with edits before submission.
But what all of these editing 'services' provide is nothing close to a rewrite of my novel. All they do is provide a few pages of feedback on what they feel isn't working. They are just pointers. They are also just opinions (ones I don't always agree with). It's up to me to fix it. It's up to me to do the work. They don't rewrite it. If they did, it wouldn't be my book anymore.
Co-authoring can be problematic in that you may not see eye to eye on the direction the book should take. You may not see eye to eye on who to, and how to, pitch it. If you do attain success, you may also not see eye to eye on how to divide any profits.
It also seems to me (and this is just me personally, other writers pitch in if you don't agree, I'd be interested to hear other points of view) that you are hoping to do the easiest part of the work (spilling out a poor first draft - and we all write poor first drafts, that's not a dig at you) and then passing the hardest part of it onto someone else while expecting (perhaps?) the largest part of, or at least half of, the reward?
What I mean is, for me personally, that shitty first draft is fun! Plotting is fun, coming up with exciting characters, writing pithy dialogue, throwing action scenes down on the page, cobbling together that first draft -- these are the most exciting aspects of writing a story. I do it pretty quickly. Once a novel is outlined, I can write a 90,000 word first draft in ten weeks, because it's not a chore. It's fun! It's the best part!
What IS a chore, is making sure those characters are fully rounded, that the dialogue is bang on and realistic, that there are no plot holes, that every line is edited until nothing can be added and nothing taken away, and the images I've created are crystal clear. Editing my ten week draft takes six months of hard hard grind.
What's EVEN MORE of a chore is selling that novel. Researching agents in the right genre, who are looking for submissions, who I'd like to work with and who actually want to work with me. Writing cover letters that sum up my novel in one line and one paragraph. Writing synopses that outline my plot while making it sound like a thrill a minute instead of a chore list of 'this happened, that happened'. And honing the first three chapters so that the submission is unputdownable.
And the actual submission process itself is probably the most gruelling of all.
So, in short, what I'm saying is that I think you'll find it difficult to get this to work.
If anyone comes to me (and this has happened a few times) and says, I've outlined this great story, will you write it for me? I think to myself, you can take a funny run and jump! You have NO idea what you're asking of me! And then, I politely say, it's your story, I think you should write it yourself.